Join input audio files and encode to MP4 using ffmpeg

encodeaudio.sh

#!/bin/bash

# the version of the script
VERSION=1.0

echo "------------------------------------------"
echo "Audio Specific Concat Script v$VERSION - A script to concatenate multiple audio files and encode to MP4."
echo "Based on FFmpeg - www.ffmpeg.org and http://goo.gl/eDFeM"
echo "------------------------------------------"

# Syntax check (has to have at least 3 params: infile1, infile2, outfile
if [ -z $3 ]; then
        echo "Syntax: $0 <input1> <input2> <input3> ... <output>"
        exit 1
fi

first=${@:1:1}
last=${@:$#:1}
len=$(($#-1))
inputs=${@:1:$len}
all_a=""

# Clean out any existing tmp files
rm -rf tmp

# Create a new tmp files dir in the current path
mkdir -p tmp

# Iterate through all the inputs and decode
i=1
for f in $inputs
do
        mkfifo tmp/mcs_a$i.mpg
        /usr/local/bin/ffmpeg -i $f -qscale:v 1 -y tmp/mcs_a$i.mpg < /dev/null &
        all_a+="tmp/mcs_a$i.mpg"
        if [ $i -lt $len ]
        then
                all_a+="|"
        fi
        let i++
done

# Concatenate all raw audio inputs
/usr/local/bin/ffmpeg -i concat:$all_a -c copy tmp/mcs_a_all.mpg

# Encode to mp4
/usr/local/bin/ffmpeg -i tmp/mcs_a_all.mpg -c:a libvo_aacenc -b:a 64k -ar 44100 -copyts -y $last

# Clean up all tmp files
rm -rf tmp

echo "----------------------------------------"
echo "*END* - audio specific join and encoding"
echo "----------------------------------------"

libvo_aacenc is the audio codec I found works best on OS X to encode f4v to H264. On Linux I found libfaac audio codec works best.